Various electronic devices include ICs. In order to protect the ICs from surge caused by ESD (electrostatic discharge), an ESD protection device as described in, for example, Patent Document 1 is connected to input/output parts of the ICs. Patent Document 1 discloses an ESD protection device with an integrated circuit formed on a semiconductor substrate, thereby achieving the reduction in size for ESD protection devices.
Patent Document 1: JP 2008-507124 W.
However, when a semiconductor substrate is exposed in an ESD protection device with an integrated circuit formed on the semiconductor substrate as in Patent Document 1, there is a possibility that a phenomenon will be caused in which the semiconductor substrate comes into contact with an outer conductor to cause ESD or noise current to flow through the semiconductor substrate into the integrated circuit, and further flow through a circuit (signal line) with the ESD protection device connected thereto.